Photozone: Please note that the tests results are not comparable across the different systems!

What part of that don't you understand?

It only means lenses are tested on specific cameras/systems so might not apply to other cameras/systems.

No. As i have already pointed out toyou in another thread, you are misinformed. What it means is that the methods used by Photozone are system-dependent and their results therefore not comparable across systems.

As I said all meaningful lens tests are system dependent that lens must work on camera bodies to take photos. So what its disclaimer only means they only tested on a specific lens-sensor combo that might not apply to other combo.

For the third time, no. Try to read it slowly and see if you can comprehend: The testing methods used by Photozone vary with the system they test. Therefore, their results are not comparable across systems.

However in reality it's meaningful to test the most popular combo directly such as on what I family with - Canon 40/2.8 pancake on FF vs similar pancake on other systems, or 24-105L walk-around zoom in FF vs 17-55/2.8 on APS-C vs similar walk-around zoom in similar range on mFT. How many people actually will use Canon 70-200L/2.8 IS II on E-M5 that will not perform much better than native Panny 35-70/2.8 OIS. So we sould compare at similar range at similar setup such as 60D+70-200L/4.0 IS vs Panny 35-100/2.8 OIS+E-M5, then DXOMark or Photozone tests are very meaningful.

Currently, I know of only two sources that use appropriate and technically well-defined measures of lens performance (MTF values) and are clear enough about their methods that I have at least some confidence in their data for purposes of cross-system comparisons: Lenstip and LensRentals. As usual, you have to be aware that the results are for the camera-lens combo, not the lens alone and, in the case of Lenstip, convert to comparable units (raw lp/mm values are not comparable across sensors of different size).

Both Lenstips and LensRental are not well known are decent lens/camera s test sites as compared to DXOMark and Photozone. I read lots of controversial on them. For example I don't know how LensRental to test lens without on a camera body?

Everyone tests with a camera body as I already pointed out. That's not the point.

But I don't base my confidence in various sites based on how well known they are (in your personal opinion). I base it on what I know about the methods used.

If you prefer to rely blindly on the authorities of your choosing (without knowing anything about testing methodology), that's your problem.

Here are some examples from LensRentals for your favorite FF equipment versus MFT (best Canon normal lens versus best MFT normal lens). The figures are line pairs per image height, center/average across the frame:

BTW, 50/1.4 (that is a 21-yr-old lens designed for film SLR) and Panny 20/1.7 are not comparable lenses.

You should compare Canon 40/2.8 STM Pancake vs Panny 20/1.7 pancake.

You should compare 50/1.4 to Panny 25/1.4 to Canon (new) 35/2.0 IS on respective system that has similar FOV. Here are DXOMark test.

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